• KIPS Transactions on Computer and Communication Systems
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• v.5 no.7
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• pp.159-172
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• 2016

This paper presents a novel algorithm for searching evacuation paths in indoor disaster environments. The proposed method significantly improves the time complexity to find the paths to the evacuation exit by introducing a light-weight Disaster Evacuation Graph (DEG) for a building in terms of the size of the graph. With the DEG, the method also considers load balancing and bottleneck capacity of the paths to the evacuation exit simultaneously. The behavior of the algorithm consists of two phases: horizontal tiering (HT) and vertical tiering (VT). The HT phase finds a possible optimal path from anywhere of a specific floor to the evacuation stairs of the floor. Thus, after finishing the HT phases of all floors in parallel the VT phase begins to integrate all results from the previous HT phases to determine a evacuation path from anywhere of a floor to the safety zone of the building that could be the entrance or the roof of the building. It should be noted that the path produced by the algorithm. And, in order to define the range of graph to process, tiering scheme is used. In order to test the performance of the method, computing times and evacuation times are compared to the existing path searching algorithms. The result shows the proposed method is better than the existing algorithms in terms of the computing time and evacuation time. It is useful in a large-scale building to find the evacuation routes for evacuees quickly.

• Journal of Navigation and Port Research
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• v.46 no.3
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• pp.209-215
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• 2022

On the Jeju coast, international cruise ships, passenger ships, and other ships pass frequently, as well as many fishing boats. Thus, there is a high risk of marine accidents and frequent ship collisions. Accordingly, it is urgent to establish a coastal VTS for systematic safety management of ships passing through the coastal waters of Jeju. The purpose of this study was to set the area of the VTS to be newly established. In this study, to calculate the workload of the VTS operators, a formula was proposed that reflects the monitoring workload considering the monitoring frequency and required time for target as well as non-target ships and the workload for ship collision situations. The proposed formula was applied to the newly established VTS area in Jeju. Three control sectors were set up in each VTS center. The average number of workstations per hour was approximately 1, so the division between sectors was appropriate. Thus, it was deduced that there would be no workload for the VTS operators. It is expected that the method proposed in this study can be used as primary data for calculating the appropriate number of workstations for the current VTS, and setting the VTS area for a new coastal VTS in the future.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2016.05a
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• pp.325-328
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• 2016

현재 완도항 VTS의 현황을 통해 관제구역 확대의 필요성과 확대될 관제구역의 예상효과를 알아보고, 예상되는 문제점과 안전하고 효율적인 관제를 위한 대응방안 제안.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2016.05a
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• pp.329-331
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• 2016

항만 내 돌풍 현상은 사전 예측이 어렵기 때문에 발생할 경우 해양사고로 이어질 가능성이 높으므로, 포항항의 실제 사례 분석을 통한 돌풍의 특징 위험성 및 VTS 대응 방안 제안.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2023.11a
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• pp.275-277
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• 2023

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.7 no.3
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• pp.17-24
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• 2008

Rail clamps are mechanical components installed to fix the container crane to its lower members against wind blast or slip. According to rail clamps should be designed to survive harsh wind loading conditions. In this study, a jaw structure, which is a part of a wedge-typed rail clamp, is optimized with respect to its strength under a severe wind loading condition. According to the classification of structural optimization, the structural optimization of a jaw is included in the category of shape optimization. Conventional structural optimization methods have difficulties in defining complex shape design variables and preventing mesh distortions. To overcome the difficulties, the metamodel using Kriging interpolation method is introduced to replace the true response by an approximate one. This research presents the shape optimization of a jaw using iterative Kriging interpolation models and a simulated annealing algorithm. The new Kriging models are iteratively constructed by refining the former Kriging models. This process is continued until the convergence criteria are satisfied. The optimum results obtained by the suggested method are compared with those obtained by the DOE (design of experiments) and VT (variation technology) methods built in ANSYS WORKBENCH.

• Korean Journal of Food Science and Technology
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• v.38 no.6
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• pp.773-778
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• 2006

The objective of this study was to evaluate three verocytotoxin-producing Escherichia coli (VTEC) detection kits to detect the presence of VT genes: Doupath Verocytotoxin (GLISA) developed by MERCK, ProsPect Shiga Toxin E. coil (STEC) Microplate Assay (ELISA) developed by Remel, and a polymerase chain reaction method. Our laboratory verified artificially inoculated samples. All three methods could detect very low numbers of VTEC, but VT-PCR had the best sensitivity for VTEC detection. From April through September 2005, 257 ground-beefs from supermakets and traditional markets were examined for the presence of VTEC by polymerase chain reaction immediately after purchase and total viable counts (TVC) were determined. VTEC was isolated from 30 of 257 ground-beefs. A variety of serogroups was found, including 10 stains belonging to the virulence type EHEC, but major serogroups such as O157, O26 and O111 were nor found.

• Journal of Korean Ophthalmic Optics Society
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• v.12 no.1
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• pp.61-67
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• 2007

The binocular functional test was performed in test of both accommodation and convergence. The balance of accommodation and convergence was important. Objects were 100 adults in 18-36 years old ages. The used apparatus was vision tester(Shinnippon VT10)and visual chart(Shinnippon CT30). Accommodative lag test by fused cross cylinder were that in case of high 39.0%, in case of low 14.0%. Negative relative accommodation were that in case of high 23.0%, in case of low 38.0%. Positive relative accommodation were that in case of high 29.0%, in case of low 23.0%. In 18% were case of low accommodation.

• Microbiology and Biotechnology Letters
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• v.30 no.4
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• pp.293-297
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• 2002

The cyclodextrin glucanotransferase (CGTase) gene from Bacillus stearothermophilus NO2 was expressed in Saccharomyces cerevisiae 2805 under the adhl promoter. The CGTase was purified from S. cerevisiae 2805/pVT-CGTS. The purified enzyme exhibited a optima of activity around pH 7.0 and $65^{\circ}C$. Thermal stability of the enzyme was increased fairly as compared with the CGTase of B. stearothermophilus NO2. The conversion yield of cyclodextrin (CD) and the production ratio of $\alpha$-, $\beta$,-, ${\gamma}$-CD from starch were showed similarly aspect to the CGTase of B. stearothermophilus NO2.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.266-267
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• 2006

A coupling capacitor voltage transformer (CCVT) is used in extra high voltage and ultra high voltage transmission systems to obtain the standard low voltage signal for protection and measurement. To obtain the high accuracy at the power system frequency, a tuning reactor is connected between a capacitor and a voltage transformer (VT). Thus, no distortion of the secondary voltage is generated when no fault occurs. However, when a fault occurs, the secondary voltage of the CCVT has some errors due to the transient components resulting from the fault. This paper proposes an algorithm for compensating the secondary voltage of the CCVT in the time domain. With the values of the secondary voltage of the CCVT, the secondary and the primary currents are obtained; then the voltage across the capacitor and the tuning reactoris calculated and then added to the measured secondary voltage. The proposed algorithm includes the effect of the non-linear characteristic of the VT and the influence of the ferro-resonance suppression circuit. Test results indicate that the algorithm can successfully compensate the distorted secondary voltage of the CCVT irrespective of the fault distance, the fault inception angle and the fault impedance.